JPH065407B2 - Transfer adjustment method in multicolor copying method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention conveys copy paper by a precharged insulating belt, and two photoconductors arranged at upstream and downstream positions in the conveyance direction. The present invention relates to a transfer adjusting method in a multi-color copying method in which images of different colors are selectively transferred from the above to obtain copy images of several kinds of copying modes corresponding to the above-mentioned color selection.

[Conventional technology]

In the above copying method, at least one photoconductor is formed by a composite photoconductor having at least two photoconductor layers having different spectral sensitivities, and the photoimage of the original is irradiated onto the photoconductor without color separation to expose the respective photoconductors. An electrostatic latent image with different polarities or electric potentials is formed on the body, and each image is visualized with two kinds of developers, and further transferred to a copy paper.
Methods are known for obtaining color reproductions. In this case, if the color of the transferred image by the copying operation using one photoconductor is a color and the color of the transferred image by the copying operation using the other photoconductor is b color, which copying operation is selected. It is possible to select five copying modes of a, b2 colors, a color removal, b color removal, all a colors, and all b colors depending on whether or not.

By the way, in the above copying operation, the copy paper is carried to the respective photoconductors by the insulating film belt. Normally, by precharging the insulating film belt, the copy paper is transferred to the belt. An operation is performed in which the voltage of the transfer charger at the time of transfer is reduced and the abnormal discharge is avoided by suction and close contact.

As an example of such a material, there is JP-A-53-74037. To do this, hold the copy paper on a pre-charged belt and perform corona discharge from the back side of the conveyor belt at each transfer position. A technique for transferring and superimposing a toner image is disclosed, and Japanese Patent Laid-Open No. 57-11183.
In No. 0, the insulating film is preliminarily charged directly before corona discharge, and at least one of this direct charge and corona discharge is controlled according to the copy paper to stabilize the transfer efficiency. The technology is disclosed.

[Problems to be Solved by the Invention]

However, these methods cannot obtain optimum transfer conditions according to the copy mode in the two-color electrophotographic apparatus capable of performing the above-mentioned copy modes.

[Means for Solving the Problems]

In view of the above points, the present invention is to provide a transfer adjusting method in a multicolor copying method capable of always maintaining good copying quality even when the copying mode is changed. The pre-charged insulating belt conveys copy paper, and images of different colors are selectively transferred from a plurality of photoconductors arranged along the conveying direction to a position facing the photoconductor across the insulation belt. In the transfer adjusting method in the multicolor copying method, in which the transferred images are transferred by the discharge action of the arranged transfer charger to obtain a copy image of several kinds of copy modes corresponding to the above color selection on the copy paper. The color of the image is different for each body,
It is possible to have multiple modes that select the image color to be transferred on the copy paper by switching the output of the transfer charger. Among the multiple transfer chargers, the voltage applied to each transfer charger is selected according to each copy mode. To make the potential fluctuation of the insulating belt due to the discharge of the transfer charger constant.

[Work]

The voltage applied to the transfer charger changes in accordance with each copy mode, and the potential fluctuation of the insulating belt for conveying copy paper due to the discharge of the transfer charger becomes constant.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, the document placed on the document table 1 is a lamp 2
It is illuminated by and reaches the half mirror 7 through the first mirror 3, the second mirror 4, the third mirror 5, and the imaging lens 6. The light beam is transmitted by the harp mirror 7 to the drum-shaped first photoconductor 11
Is divided into a second light flux directed toward the second photoconductor 12 having a drum shape.

The first light flux reflected by the half mirror 7 is the fourth mirror 8,
The light enters the first photoconductor 11, for example, the photoconductor for red, through the fifth mirror 9 and is exposed.

The second light flux passing through the half mirror 7 is the sixth mirror 10
And is incident on the second photoconductor 12, for example, the black photoconductor, and is exposed.

Two colors, black and red, will be described below, but the colors are not particularly limited to these two colors.

A focus correction glass 13 and a diaphragm 1 are provided in the path of the first light flux for red.
4, a filter 15 and a diaphragm 16 are provided in the passage of the second light flux for black.

A primary charging device 17, a secondary charging device 18, an exposure position 19, a developing device 20, a first transfer charger 21, a cleaning device 22 and a potential erasing lamp 23 are arranged around the first photoconductor 11 in the rotation direction of the photoconductor. Are arranged in sequence,
An electrostatic latent image of only a red image is formed by utilizing the difference in spectral sensitivity of the photoconductive layer of the photoconductor, and this latent image is visualized by the red developer at the developing position 20, which is then insulated by the insulating film belt 24. Transfer to the copy paper conveyed by. After the transfer, the photosensitive member is cleaned and discharged to complete one cycle.

Similarly, a temporary charging device 17 'is provided around the second photoconductor 12.
(In the case of black, the secondary charging device can be omitted), the exposure device 19 ', the developing device 20' (the first photoconductor 1).
A color different from that of the developing device 20 arranged in No. 2, for example, a black developer is stored), a second transfer charger 21 ', a cleaning device 22', and a potential erasing LED 23 'are arranged in the same manner as the first photoconductor 11. The black image is transferred to the copy paper conveyed by the insulating film belt 24.

The transfer paper is sent from the paper feed tray 26 by the paper feed roller 27, temporarily stopped by the registration rollers 34 and 35, and then re-fed toward the insulating film belt at a predetermined timing.

The insulating film belt 24 is made of a dielectric material and is wound around a driving roller 36 and a driven roller 37, its deviation is corrected by a correction roller 38, and a belt position detector 39 passes the joint, that is, a home position. Is detected.

The belt 24 stops and stands by immediately after the passage position detection 39 detects the passage of the seam. Further, the belt 24 starts in synchronization with the start of the pair of registration rollers 34, 35, and is given a predetermined charge by a precharge charger 28 arranged so as to face the correction roller 38 to be precharged to a predetermined potential. This preliminary charge amount can be changed for the reason described below.

When the copy paper reaches the pre-charged insulating film belt 24, the copy paper is electrostatically adsorbed by the belt, and the belt 24 is conveyed without relative slippage.

While the copy paper is being conveyed, the first photoconductor 11 is de-charged by the pre-transfer charge eliminating lamp 43, and then the copy paper shows a visible image (for example, a red image) of the first photoconductor 11 under the action of the first transfer charger 21. Transferred, then second transfer charger 21 '
Under the action of, the visible image (for example, a black image) of the second photoconductor 12 is transferred.

After the transfer, the photoconductors 11 and 12 are cleaned and removed if necessary, and the steps from the primary charging are repeated. On the other hand, the copy sheet after transfer is separated from the belt 24 by the action of the separation charger 29 and the separation claw 30, is fixed while passing between the fixing roller 31 and the pressure roller 32, and is delivered to the paper discharge tray 33. At this time, it contacts the discharge brush 44 to discharge the charged electric charge.

After the copy paper is separated, the insulating film belt 24 is cleaned by the cleaning blade 40 to remove the attached developer, and the charge removal charger 42 for the counter electrode plate 41 is removed.
The electric charge is removed by the electric discharge by and the belt position detector 39 detects and stops at the standby position.

A copying operation using the first photoconductor 11 as described above (hereinafter,
If copying is performed by both the copying operation using the first copying operation) and the copying operation using the second photoconductor 13 (hereinafter referred to as the second copying operation), a copying image in a copying mode of two colors of red and black is obtained on the copying paper. To be On the other hand, if only the first copying operation is performed, black or full red mode copying can be obtained, while the second copying operation is performed.
If only the copying operation is performed, the red or all black mode copying can be obtained.

As described above, in the first copying operation and the second copying operation, transfer is performed by the transfer chargers 21 and 21 ', respectively. Generally, the transfer efficiency at that time is from the transfer charger to the insulating film belt 24. It is determined by the charge applied. When applied to the insulating film belt 24, the potential of the belt 24 rises accordingly. Therefore, the transfer efficiency of the transfer charger can be estimated by the potential fluctuation of the belt after being subjected to the transfer action by the transfer charger.

FIG. 2 shows the transfer efficiency with respect to the potential fluctuation of the belt after the transfer charger is discharged. The figure shows that
The highest transfer efficiency is when the belt potential fluctuation is 1300 to
It means that it is 1500 V, and efficiency is gradually decreased below that, and sharply decreases above that. It is considered that the efficiency is low at a small potential fluctuation due to insufficient charging of the belt, and the efficiency is low at a large potential fluctuation due to excessive charging.

From this result, in order to obtain a good transfer efficiency in the copying machine of FIG. 1, it is desirable that the potential fluctuation of the belt 24 due to the discharge of the first transfer charger 21 and the second transfer charger 21 ′ is set to 1300 to 1500V. .

Hereinafter, in the copying machine shown in FIG.
Transfer charger 2 with a constant amount of belt charge by
By adjusting the applied voltage or current to 1 ',
For adjusting the fluctuation of the charging potential of the belt before and after the transfer charger 21 or 21 '(that is, adjusting the charge applied to the belt), thereby performing the efficient transfer in the first and second copying operations. A specific example will be described.

First, the transfer conditions in the two-color mode will be described with reference to FIG. In this case, the spare charger 2 as shown
8, the insulating film belt 24 is 1 = about -500.
Charge to V. As described above, the electrostatic charge is applied to the copy paper on the belt 24 by this charging.

In order to charge the belt 24 to -500V, a voltage of about 4.5KV is applied to the preliminary charger 28. The belt 24 thus precharged is conveyed to the first transfer charger 21 together with the copy paper to be adsorbed and held, and the potential fluctuation is reduced to 1
It is subjected to a discharge action to the extent of 300V, that is, the belt potential after the charger becomes approximately V2 = 800V. At this time, a red image is transferred from the first photoconductor 11 to the copy paper. A voltage of about 5.5 KV is applied to the first transfer charger 21 so that V2 = 800 V or so.

The copy paper and belt that have completed the first copy in this manner are then carried to the second transfer charger 21 '. The second transfer charger 21 ′ is V2 = by the first transfer charger 21.
Based on the belt potential raised to 800V,
Discharge is performed so that the voltage is further raised by about 1300V. The applied voltage at this time is about 6.5 KV. At the time of this discharge, a black image is transferred from the second photoconductor 12 to the copy paper.

The two-color mode copying is performed as described above.

Next, the transfer condition in the case of the all-red or black outline mode in which only the first copying operation is performed will be described.

In this case, as shown in FIG. 4, of the transfer conditions in the two-color mode shown in FIG. 3, since the second copying operation is not performed, application to the second copying charger 21 'is performed. The voltage may be 0 V, and the other conditions may be exactly the same as the transfer conditions in the two-color mode. As a result, the potential on the belt 24 becomes V1 = -500V, V2 = V3 = 800V.

Next, the transfer conditions in the all black or red removal mode in which only the second copying operation is performed will be described. FIG. 5 shows the conditions, and as shown in the figure, the pre-charge in this case is V1 = −500V as in the above case. The precharged belt 24 passes through the first transfer charger 21 and is conveyed to the second transfer charger 21 ′ while adsorbing and holding the copy paper. Since the first copying operation is not performed, no charge is applied from the first transfer charger 21, and therefore the preliminary charging V1 is held as it is as the potential V2 after the first transfer charger. The potential of the belt 24 charged to V1 = V2 = −500V is 1300 due to the discharge of the second transfer charger 21 ′.
Increase by about V and set V3 = 800. In this case, the voltage applied to the second transfer charger 21 'is 5.5 KV. It is the first that efficient transfer is performed during this potential rise.
In the case of the above transfer conditions in which only the copying operation is performed (4th
(Fig.).

The broken line in FIG. 5 indicates the one in the all black or red extraction mode, that is, in the second copying operation, but in the two-color mode as the transfer condition, that is, the voltage applied to the second transfer charger 21 'is 6.
It shows a state in the case of 5 KV. In this case, since the belt potential before entering the second transfer charger 21 'is low, the belt potential fluctuation after discharge is extremely large, for example, about 1900V. Belt 2 when this happens
4 and the copy paper on the belt are given an excessive electric charge, resulting in a transfer failure.

On the other hand, under the main transfer condition in which V3−V2 (V1) = 1300V is suppressed, there is no fear of such transfer failure.

〔The invention's effect〕

As described above, according to the present invention, the applied voltage to the transfer charger of the photoconductor on the downstream side in the belt conveying direction is changed according to each copy mode, so that a stable transfer image is obtained irrespective of the copy mode. Easy to get.

[Brief description of drawings]

FIG. 1 is an overall side sectional view of a two-color copying machine using the method of the present invention, FIG. 2 is a graph showing the relationship between fluctuations in belt potential due to discharge of a transfer charger and transfer efficiency, and FIG. FIG. 4 is a graph showing an example of charging conditions in the 2-color copy mode, FIG. 4 is a graph showing an example of charging conditions in the 1-color copy mode, and FIG. 5 is an example of charging conditions in the other 1-color copy mode. It is a graph shown. 24 ... Insulating belt, 11, 12 ... Photoconductor, 2
1, 21 '... Transfer charger, 28 ... Pre-charger.

Claims (1)

[Claims] 1. A copy sheet is conveyed by a precharged insulating belt, and an image of a different color is selectively selected from a plurality of photoconductors arranged along the conveying direction with the photoconductor with the insulating belt interposed therebetween. In the transfer adjustment method in the multicolor copying method, which is performed by the discharge action of the transfer chargers arranged at the opposite positions to obtain a copy image of several kinds of copy modes corresponding to the above color selection, It is possible to have a plurality of copy modes, each of which has a different image forming color for each photoconductor of the body, and the image color transferred on the copy paper is selected by switching the output of the transfer charger. Among the plurality of transfer chargers, the voltage applied to each transfer charger is varied according to the copy mode, and the potential fluctuation of the insulating belt due to the discharge of the transfer charger is made constant. Method for controlling transfer in multicolor copying method.